Spot welding systems using robots with spot welding guns are well known and widely adopted in an assembling process of an automobile body, for example. In general, the spot welding is not carried out only on a single welding spot but is practically carried out on a number of welding spots, especially in the assembling process of an automobile body.
Thus, in conventional spot welding systems, there is adopted a layout in which a plurality of articulated robots are arranged in a row to laterally project from an upright wall or to be suspended from a structure such as a ceiling or a beam. In some cases, instead of using an existing structure, a frame dedicated for installing robots is provided.
An object of welding such as an automobile body is transferred along a line which passes near the robots arranged in a row. Usually, the transferring action is intermittently repeated to stop successively at respective operating stages, where the spot welding is carried out on required spots.
However, in the conventional spot welding system using articulated robots encompass problems in efficiency of operation and space utilization. Specifically, it is difficult to arrange the articulated robots close to one another because of their structure or shape, and therefore it is impossible to take advantage of a high-density layout for improving the operational efficiency and for saving space.